Method for mounting a pipe in a perforated plate

ABSTRACT

The pipe is fitted with at least a pair of explosive members, one of which serves to weld the pipe to the perforated plate while the other serves to expand the pipe into bearing contact with the plate. The detonation of the two members takes place in the same operation. A third explosive member can also be fitted in the pipe for welding the pipe to an opposite side of the plate.

United States Patent Feiss METHOD FOR MOUNTING A PIPE IN A PERFORATED PLATE [72] inventor: Rene '1. Feiss, Winterthur, Switzerland [73] Assignee: Sulzer Brothers Ltd., Winterthur,

Switzerland [22] Filed: Sept. 4, 1970 [21] Appl. No.: 69,703

[30] Foreign Application Priority Data Sept. 23, 1969 Switzerland ..0l4326/69 [51] Int. Cl. .3231: 21/00 [58] Field of Search ...29/421 E, 473.3, 474.3, 470.2, 29/4701, 486, 497.5, 475

[ 1 Oct. 17, 1972 3,313,021 4/1967 Wright et a1. ..29/42l E 3,411,198 11/1968 Berman et a1 ..29/474.3 X 3,411,687 11/1968 Riley et a1. ..29/42| E X 3,426,681 2/1969 Oliver ..29/42l E X 3,446,047 5/1969 Cleland ..29/421 E X 3,503,110 3/1970 Berry et a1 ..29/42| E X 3,566,649 3/1971 McSmith ..29/421 E X 3,590,877 7/1971 Leopold et al. ..29/42l E Primary Examiner.lohn F Campbell Assistant Examiner-Richard Bernard Lazarus Attorney-Kenyon and Kenyon Reilly Carr and Chapin 5 7 ABSTRACT The pipe is fitted with at least a pair of explosive members, one of which serves to weld the pipe to the perforated plate while the other serves to expand the pipe into bearing contact with the plate. The detonation of the two members takes place in the same operation. A third explosive member can also be fitted in the pipe for welding the pipe to an opposite side of 8 Claims, 4 Drawing Figures ll' 'lll PATENTEDUBI 17 I972 SHEU 2 BF 4 mu m mu 5 PATENTEDom n ma SHEET 3 BF 4 lll' llll lllflIlll'il'llllil'"!!!g'll! GEL a Inventor RENE F's/5s 5y ,w 7flg%zgwwg y flTrO/VEYS PHENTED B 17 I97? 3.698.067

sum u or 4 p- III Inventor:

REN Fez/as METHOD FOR MOUNTING A PIPE IN A PERFORATED PLATE This invention relates to an apparatus and method for mounting a pipe in a perforated plate and, more particularly, to an apparatus and method for mounting the pipe by means of explosive pressure waves.

It has recently become known that pipes can be mounted in a perforated plate by the application of explosive pressure wave technology, that is, by the explosion of a charge in the interior of a pipe. For example, two techniques have been provided. In one, attempts have been made to expand the pipes by means of explosive pressure waves in order to bring the pipes to bear on the wall of a bore within a plate. This method has been particularly recommended if the perforated plate is very thick relative to the diameter of the bore, for example, in the case of a pipe end plate of a high pressure heat exchanger. In the other technique, part of the insertion length of the pipe is metallically joined or welded to the perforated plate in the bore by-means of explosive pressure waves. However, in this case only a very small part of the residual insertion length of the pipe is expanded at best and made to bear in the bore on the perforated plate. Further, if the perforated plate has a thickness which amounts to a multiple of the pipe diameter, slack remains between the pipe and the perforated plate over the greater part of the insertion length and gap corrosion is liable to arise.

Accordingly, it is an object of the invention to expand a pipe within a perforated plate and to weld the pipe to the perforated plate in the same operation.

It is another object of the invention to eliminate gap corrosion between a plate and a pipe mounted within the plate.

It is another object of the invention to secure a pipe in a plate so that the pipe is welded and is additionally expanded over the greater part of its insertion length.

Briefly, the invention provides a method and apparatus of expanding a part of a pipe located within a bore of a plate while welding another part of the pipe within the bore to the plate.

The method of the invention includes the step of exploding a first explosive charge positioned within a first zone of a pipe to cause the pipe to become welded to the plate in the first zone by means of a explosive pressure wave while, in the same operation, exploding a second explosive charge positioned within a second zone of the pipe to cause the pipe to expand into bearing contact with the plate in this second zone.

In another embodiment, the pipe is expanded over the greater part of its insertion length with a perforated plate and is welded to the plate at two different zones. To this end, the pipe is welded by means of first charge in one zone of the pipe to the plate, expanded by means of a second charge in a second zone to bear against the plate and welded by means of a third charge in a third zone to the plate. It is advantageous to perform the welding on the two sides of the pipe disposed closely adjacent the two sides of the perforated plate since gap corrosion can then be completely excluded.

The apparatus of the invention is constructed to cooperate with a pipe which is inserted within a bore of a perforated plate. This apparatus, in one embodiment, includes a first explosive charge which is positioned within the pipe in a first zone and a second explosive charge which is positioned within the pipe in a second zone. These two charges are of different detonation characteristics whereby the first charge is sufficient upon detonation to weld the pipe to the bore wall of the plate while the second charge is sufficient upon detonation to expand the pipe into bearing contact with the bore wall within the second zone. In addition, the charges can be mounted within a suitable resilient pressure transmitting means, such as a tubular insert, so as to be mounted within a pipe as a unit. Such a means can be constructed to prevent entry of any particles of the exploded charges into the interior of the pipe spaced from the plane of the plate and to permit an accurate placement of the charges within the pipe.

in another embodiment of the apparatus, an additional explosive charge can be used to weld the pipe to the plate at another spaced apart zone from the zone of the first weld.

These and other objects and advantages of the invention become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a part cross-sectional view of an apparatus according to the invention in place within a P p FIG. 1 illustrates a view similar to FlG. l of a modified apparatus according to the invention;

FIG. 3 illustrates a view similar to FIG. 2 of another modified apparatus according to the invention; and

FIG. 4 illustrates a view similar to FIG. 1 of an apparatus according to the invention for welding a pipe in two zones to a plate.

Referring to FIG. 1, a pipe 3 is disposed in a bore I of a perforated plate 2, for example. the pipe end plate of a heat exchanger to be secured therein and is of an insertion length equal to the thickness of the plate 2. The pipe 3 is provided with a portion 4 of smaller diameter than the bore 1 so that an annular gap 5 is disposed between the outer surface 6 of the pipe and the wall 7 of the bore 1. This portion 4 of the pipe 3 is the portion which is to be metallically joined or welded to the pipe end plate 2. The annular gap 5 ensures that the pipe wall in this zone can be accelerated to an adequate velocity before striking the wall 7 of the bore 1, a condition which is a prerequisite for the establishment of the weld. The inserted pipe 1 is provided with two collars 10, 11 to ensure that it is disposed concentrically in the bore 1 of the pipe end plate 2. In this case, the collars 10, 11 are hydraulically produced expansions of the pipe 3. The non-expanded part 12 of the pipe between the collars 10, l 1 forms a uniform annular gap 13 with the bore 1. The collar 10 is also provided to avoid any slack at the rear end 14 of the pipe end plate 2 since it is not possible, or only with difficulty, to control the pressure wave to such an extent that the wave causes the pipe 3 to bear reliably on the wall 2 of the bore 1 as far as the rear end 14 of the pipe end plate 2 without inflating the pipe 3 near the emerging position 15. However, gaps are always undesirable since they give rise to gap corrosion.

In order to provide for the welding and expansion of the pipe 3 to the end plate 2, a resilient pressure transmission insert 20 is disposed in the pipe 3. This insert 20 has a base 21 which closes the pipe 3 on one side and prevents products of the explosion being thrown into the pipe 3. In addition, a plastics sleeve 22 is inserted into the pressure transmission insert 20 and contains in that sequence a detonating cartridge 23, a first explosive charge or explosive member 24, and a second explosive charge 25 adjoining the first charge 24. Both explosive charges 24, 25 may be in the form of an explosive cord with plastics sheath. The sleeve 22 is provided with two grooves 26, 27 in the outer surface into which detonating conductors 28, 29 of the detonating cartridge 23 are installed and extended to an exploder (not shown) as well as with two apertures 30, 31 through which the detonating conductors 28, 29 pass to the cartridge 23. In order to close off the bore 1, a collar 32 is provided on the pressure transmission insert 20. This prevents fumes of the explosion from reaching the welding zone since the fumes have a corrosive effeet.

In operation, in order to mount the pipe 3 in the pipe end plate 2, the detonating cartridge 23 is operated by the exploder (not shown) as is known. The detonating cartridge 23 then detonates the first explosive member 24. The pressure waves resulting from this explosion cause the pipe 3 to be expanded over the entire length of the part 12 between the hydraulically produced expansion collars l and 11 so that the external circumference of the pipe 3 bears firmly at that position on the internal wall surface of the bore 1 in the pipe end plate 2. At the moment at which the travelling detonation of the first explosive member 24 reaches the second explosive member 25, the second member 25 becomes detonated. The pressure waves resulting from the detonation of the second explosive member 25 weld the portion 4 of the pipe 3 with the reduced diameter to the internal wall 7 of the bore 1. Since the pipe 3 has already been expanded and therefore anchored by the explosive member 24, any motion of the pipe 3 during the subsequent welding operation is thus made impossible.

The charges of the two explosive members 24 and 25 are adapted to their functions, namely the expansion or welding respectively of the pipe, that is, the charge of the explosive member 25 used to weld is greater than that of the explosive member 24 used to expand. The greater charge may, for example, be obtained by making the internal diameter of the pressure "transmission insert 20 in the welding zone greater than in the expansion zone so that a larger quantity of explosive substance may be accommodated thereat. Moreover, it is possible for different detonation rates or velocities to be selected for both explosive members 24, 25. [t is advantageous if the detonation rate of the explosive member 24 for expanding the pipe is made large since a substantial expansion effect can be achieved with a small quantity of explosive substance. By contrast, the detonation velocity of the explosive member 25 for the welding operation may be made smaller. Also, the detonation velocity of the explosive member 24 for expansion is greater than the sonic velocity in the pipe wall.

Referring to FIG. 2, a bore 35 in a pipe end plate 36 is provided with a slightly flared expanded portion 33 at one side which is disposed near the end 37 of a pipe 39 which is inserted therein. Half the apex angle of the expansion is designated with a. A pressure transmission insert 40 provided with a collar 41 is inserted into the pipe 39 as far as the abutment of the collar 41 with the pipe end 31. The pressure transmission insert 40 is also provided'with a longitudinal bore 42 in which an explosive charge or an explosive member 43 in the form of an explosive cord is disposed with a damping medium 45 being disposed in the forward remaining space 44 of the longitudinal bore 42. The pressure transmission insert 40 also has a blind hole 46 with a tapered floor 47 disposed on the collar side. A cup-shaped explosive charge or explosive member 48 is disposed in the blind hole 46 and has a peripheral wall and a conical base 49 with a bore 50 passing therethrough of a diameter which corresponds to the diameter of the explosive member 43. The space remaining between the explosive member 43 and the peripheral wall of the explosive member 48 is filled by a metal tube 51 which extends outwardly beyond the collar 41 of the pressure transmitting insert 40.

In order to secure the pipe 39 in the pipe end plate 36, the explosive member 43 is detonated at the righthand end as viewed. The explosive member 43 then detonates in the direction of the pipe 39, that is, from right to lefi as viewed. During detonation, the metal pipe 51 elastically absorbs the greater portion of the thrust energy so that hardly any deformation of the pipe 39 occurs in the zone of the metal pipe 51. As soon as the detonation passes the end 52 of the metal pipe 51, the pipe 39 will be expanded over the remaining length of the explosive member 43 and will thus be secured in the bore 35. The damping medium 45 comprising, for example, an expanded substance based on polyurethane, prevents excessive back pressure of the explosive wave front. At the moment at which the detonation of the explosive member 43 reaches the base 49 of the explosive member 48 this member 48 becomes detonated. The detonation of the member 48 then travels in the opposite direction from left to right as viewed while welding the pipe end 53 to the pipe end plate 36. In this system, two detonations travelling simultaneously in opposite directions from one point are produced by means of a single detonation introduced from the exterior into the pipe 39.

Referring to FIG. 3, instead of securing a pipe in an end plate having a flared portion with an apparatus as in FIG. 2, a tubular pressure transmission insert 65 is provided with an explosive member 66 adjoining a detonating cartridge 67 which, in turn, is surrounded by an explosive member 68 in the form of an explosive with The explosive member 66, once again having the form of an explosive cord, serves to expand aiength of a pipe 69 inserted in a pipe end plate 70 while the explosive foil 68 serves to weld the end of the pipe 69 to the pipe end plate 70. Both explosive members 66, 68 are detonated simultaneously by the detonating cartridge 67 so that expansion and welding proceed practically simultaneously.

Referring to FIG. 4, in order to weld a pipe to a pipe end plate 76 at the two ends of the plate 76, the bore of the perforated plate 76 is provided on the front side 77 with a conical portion 78 while the rear or pipe nest side 79 of the bore 75 is provided with a conical portion 80 and a contiguous cylindrical portion 81. The interior of the pipe is, as above, provided with a pressure transmitting insert 82 in which a detonating cartridge 85 with detonating wires 86, 87 an adjoining explosive member 88 which extends over the greater portion of the insertion length of the pipe, and an adjoining explosive member 89 are disposed. The explosive member 88 adjacent the cartridge 85 serves to expand the pipe when exploded while the next explosive member 89 serves to weld the pipe to the pipe end plate 76 near the end of the pipe. The detonating cartridge 85 is disposed partially within a cup-shaped explosive member 90 which is centered therein by means of an insert 91. The pressure transmitting insert 82 is closed on the pipe nest side by a plug 83 firmly joined thereto so that the detonating cartridge 85 cannot be driven into the interior of the pipe as by a reaction effect. Moreover, corrosive fumes are prevented from ingressing into the interior of the pipe. The pipe end side of the pressure transmitting insert 82 is also closed by a plug 84 which prevents the ingress of fumes into the weld zone.

In order to secure the pipe in the pipe end plate 76, the detonating cartridge 85 is detonated and in turn initiates the combustion of the cup-shaped explosive member 90 and of the explosive member 88. The pressure waves issuing from the explosive member 90 causes the pipe to be welded to the perforated plate on the pipe nest side 79 in the same manner as described above in reference to FIG. 2. The cylindrical part 81 of the bore 75 prevents the pipe from being inflated outside the pipe and plate so that inflation is therefore confined to the cylindrical part 81 of the bore 75. The combustion of the explosive member 88 is accompanied by an expansion of the pipe which is brought to bear upon the internal wall of the bore 75. When combustion reaches the end of the explosive member 88, the member 88 detonates the explosive member 89 which welds the pipe to the perforated plate via the conical part of the bore.

Instead of preventing inflation of the pipe on the pipe nest side 79 by means of the cylindrical part 81, a damping means, for example, in the form of a liquid stratum of the perforated plate if the pipe nest is vertically positioned, can be used. Such a damping means can also be used with the cylindrical part 81. The advantage of this is that the explosive charge 90 can be brought even closer to the weld zone.

It is noted that the various perforated plates described above may be provided with a hood to reduce noise nuisance during the mounting operation and the hood may be evacuated.

The invention thus makes it possible on the one hand to weld a pipe to a perforated plate and on the other hand to expand the pipe over the greater part of the insertion length within the plate to thus avoid gap corrosion.

What is claimed is:

l. A method of mounting a pipe in a bore of a thick perforated plate which comprises the steps of welding a first part of the pipe to the plate in a first zone of said bore under an explosive pressure wave created by a first explosive member, and expanding a second part of the pipe to the plate in a second zone of said bore under a second explosive pressure wave created by a second explosive member in the same operation.

2. A method as set forth in claim 1 which further comprises the steps of welding a third part of the pipe to the plate in a third zone of said bore under a third explosive pressure wave created by a third explosive member in s id operatio 3. A met 0d as set forth in claim 2 wherein the second explosive member initiates the detonation of the first and third explosive members.

4. A method as set forth in claim 2 wherein said first and third zones are disposed on two opposite sides of the perforated plate.

5. A method as set forth in claim 1 wherein the second explosive member initiates detonation of the first explosive member.

6. A method as set forth in claim 1 wherein the first and second explosive members are detonated simultaneously by a detonating cartridge.

7. A method as set forth in claim 1 wherein the explosive members are detonated at a common detonating point by a single detonation introduced from the exterior on one side into the pipe, the detonations of both explosive members proceeding simultaneously and in opposite directions from said detonating point.

8. A method as set forth in claim 1 wherein said first zone is near the pipe end.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,698,067 Dated October 17, 1972 Rene T. Feiss Patent No.

Inventor(s) t error appears in the above-identified patent It is certified the y corrected as shown below:

and that said Letters Patent are hereb Column M, line 50, "explosive with The" should be --e JPIOSiVQ foil. The-- Signed and sealed this 15th day of May 1973.

(SEAL) Attest:

ROBERT GOTTSCHALK EDWARD M.FLETCHER,JR. Attesting Officer Commissioner of Patents FORM PC4050 ($691 USCOMM-DC scam-P09 U,5. GOVERNMENT PRINTING OFFICE. 9'9 355-334 

1. A method of mounting a pipe in a bore of a thick perforated plate which comprises the steps of welding a first part of the pipe to the plate in a first zone of said bore under an explosive pressure wave created by a first explosive member, and expanding a second part of the pipe to the plate in a second zone of said bore under a second explosive pressure wave created by a second explosive member in the same operation.
 2. A method as set forth in claim 1 which further comprises the steps of welding a third part of the pipe to the plate in a third zone of said bore under a third explosive pressure wave created by a third explosive member in said operation.
 3. A method as set forth in claim 2 wherein the second explosive member initiates the detonation of the first and third explosive members.
 4. A method as set forth in claim 2 wherein said first and third zones are disposed on two opposite sides of the perforated plate.
 5. A method as set forth in claim 1 wherein the second explosive member initiates detonation of the first explosive member.
 6. A method as set forth in claim 1 wherein the first and second explosive members are detonated simultaneously by a detonating cartridge.
 7. A method as set forth in claim 1 wherein the explosive members are detonated at a common detonating point by a single detonation introduced from the exterior on one side into the pipe, the detonations of both explosive members proceeding simultaneously and in opposite directions from said detonating point.
 8. A method as set forth in claim 1 wherein said first zone is near the pipe end. 